Hey I just bought this second hand so I don't have a manual or anything, I worked out how to switch from volume to wah, but I can't work out how to switch it to tweak mode so it acts as an expression pedal for some stomp boxes (eg, bender) I know it can be done because some presets already have it done, and both lights for volume and wah light up when the mode is in use. It's probably simple but can anyone help me?? I want to be able to use it as a whammy etc as well. Thanks in advance